文摘
In this paper, the different tunneling decay constants 尾N of alkanedicarboxylic acids depending on the metal electrodes in various surroundings are discussed. The conductance of alkanedicarboxylic acids (HOOC鈥?CH2)n鈥揅OOH, n = 2鈥?) contacting to Pd and Ag were systematically measured by the scanning tunneling microscopy (STM) break junction (STM-BJ) in air. A similar tunneling decay constant 尾N of about 1 per 鈭扖H2 was found for both metals, which might arise from the Fermi energy of electrodes pinning with the energy positions of molecular states under ambient atmosphere. However, the pinning effect can be destroyed by potential control in electrochemistry, and the 尾N is determined by the alignment of the molecular energy levels relative to the Fermi energy level of the electrodes, which well explains the order of 尾N,Pd < 尾N,Ag < 尾N,Cu in electrochemistry. The current work shows the important role of the surroundings in electron transport through molecular junctions.
